Cartridge tube for rifle grenade capable of retaining the bullet fragments

ABSTRACT

A cartridge tube for a grenade capable of being fired by a live round of a weapon has a bullet trap to stop the bullet and a plug made of a deformable material to prevent the fragments produced when the bullet impacts on the bullet trap from escaping from the cartridge tube. The plug bears against a wall positioned between the plug and the bullet trap. The wall is attached to the cartridge tube and is substantially perpendicular to the center-line of the tube. The wall is positioned at a distance from the bullet trap along the center-line of the cartridge tube, thus establishing an empty space between the wall and the bullet trap.

BACKGROUND OF THE INVENTION

The present invention concerns a rifle grenade and, more precisely, thecartridge tube which is disposed at one end of the said grenade wherebyit can be placed on the barrel of a rifle.

The cartridge tube of a rifle grenade contains a bullet trap accordingto prior art which, by stopping the bullet, allows the grenade to befired by means of any kind of munition and in particular a livecartridge.

The deceleration of the bullet by the trap generates metal fragments(such as pieces of the bullet casing) and these fragments are ejected inthe direction of the firer when the grenade leaves the barrel of therifle.

These fragments are ejected even more violently when an additionalpropellant charge is placed in the cartridge tube. Attempts have alreadybeen made to limit or prevent such ejections by placing a plate made ofelastic material at the entry to the bullet trap.

Reference may be made for example to French patent 1599746 whichdescribes a bullet trap on which a plate made of an elastic plasticsmaterial is placed. The plate is penetrated by the bullet and closesagain immediately thereafter, thus preventing fragments from beingejected towards the firer.

French patent 2517820 also describes a bullet trap for rifle grenadeswhich incorporates a steel trap with a washer made of a damping materialarranged inside a support tube. The trap is closed by a woven nylon capthe function of which is to protect the firer against the bulletfragments and which is tightly fitted or bonded to both the cartridgecase and the trap.

Experience shows that these solutions are unsatisfactory and that bulletfragments are still projected out of the cartridge tube.

SUMMARY OF THE INVENTION

An object of the invention is to provide a cartridge tube which createsbetter protection for the firer by retaining the fragments of the bulletwith greater efficiency than the known systems described above.

The subject of the invention is therefore a cartridge tube for a grenadecapable of being fired from a weapon by a live munition, the tubecontaining first a bullet trap designed to stop the bullet and,secondly, a plug made of a deformable material, designed to prevent thefragments produced by the impact of the bullet on the bullet trap fromescaping from the cartridge tube, this tube being characterised by thefact that the plug bears against a wall positioned between the plug andthe bullet trap, the wall being attached to the cartridge tube andsubstantially perpendicular to the center line of the said tube, thewall being positioned at a distance from the bullet trap along thecenter line of the cartridge tube, thus establishing an empty spacebetween the wall and the bullet trap.

This arrangement prevents any interference between the wall upon whichthe plug bears and the bullet trap at the time of impact of the bulleton the said trap. The wall also grips the plug which assists itsreclosure after passage of the bullet.

The wall is attached to a support which is itself fastened to thecartridge tube and includes a bore which retains an outer surface of theplug.

This arrangement facilitates the fitting of the plug and improves itsretention as well as its closure following its penetration by thebullet. Preferably, there is a concave depression in the surface of theplug facing the wall.

In a variant, the plug has notches distributed regularly over its outersurface. Also, there may be an opening in the wall of diameter greaterthan the diameter of the bullet.

The rear portion of the plug may have a smaller diameter than the borein the support.

In a first embodiment of the invention, the support has a bearingsurface against which the plug bears and the wall is attached to a capwhich closes off the bore and presses the plug against the bearingsurface.

In a variant, the support contains a certain number of orifices throughwhich some of the propellant gases generated by the munition forigniting a rocket can pass and it also has a sealing ring fitted firstto an outer surface of the bullet trap and secondly to a cylindricalextension of the cap.

According to another characteristic, the cylindrical extension of thecap constitutes a spacer which bears against the bullet trap andmaintains the trap at a given distance from the wall.

In a second embodiment of the invention, the support has an end on whichit bears and this end constitutes the wall. According to anothercharacteristic, the bore in the support has an annular rim designed toretain the plug in an axial direction.

The distance between the deformable plug and that part of the bullettrap on which the bullet first makes contact will advantageously begreater than the total length of the bullet.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood from a reading of the followingdescription of particular embodiments, with reference to the attacheddrawings in which:

FIG. 1 is a longitudinal section of a cartridge tube according to afirst embodiment of the invention;

FIG. 2 is a longitudinal section of a cartridge tube according to asecond embodiment of the invention;

FIG. 3 shows a different variant of the plug support;

FIG. 4 is a longitudinal section of a cartridge tube according to athird embodiment of the invention;

FIG. 5a is a rear view of the support used in the third embodiment, and

FIG. 5b is a front view of the plug used in this third embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to FIG. 1, a cartridge tube 1 is designed to be attachedto a rifle grenade (not shown). It has a rear part 2 which carriesstabilization fins 3 in which a bore 4 is made allowing it to be placedon the end of a rifle barrel.

The cartridge tube also has a front part 5 which has a threaded zone 6on its outer surface whereby it can be attached to a grenade of a knowntype (for example an anti-tank or anti-personnel grenade).

The front part 5 has a substantially cylindrical internal recess 7inside which a bullet trap 8 of a known type (that described in patentFR 2543284) is positioned.

The internal recess 7 in the front part 5 is separated from the bore 4in the rear part by a partition wall 9 the central part 10 of which hasreduced thickness to facilitate penetration by the bullet (such astructure is described in patent FR 2605399).

The end of the internal recess 7 constitutes a cavity 11 which isbounded at the rear end by the partition wall 9 and at the end facingthe bullet trap 8 by a support 12 in which a plug 13 is fitted.

The cavity 11 is filled by a propellant powder (not shown) ignited bythe passage of the bullet and which serves to increase the range of thegrenade in a known manner.

The support 12 has symmetry of revolution and it is threaded on thecartridge tube 1. Support 12 comprises a bore 14 and an end constitutinga wall 15 which therefore lies between the plug 13 and the bullet trap8. The bore 14 retains an outer surface of the plug 13.

The plug is held against the wall 15 by an elastic washer 16 fitted inan annular groove on the support 12.

The plug has a rear part 29 having a diameter which is slightly less (byabout 1 to 2 mm) than that of the bore 14. The plug here is made from anelastomer of the polyurethane type whose hardness is 90 Shore A.

Another elastic material, which may or may not be a composite, withhardness for example between 80 Shore A and 60 Shore D could be used.

The plug has a concave depression 25 of spherical section made on thesurface which bears against the wall 15.

This depression allows deformation of the plug which facilitatespenetration of the plug by the bullet. The support is made of aluminium,but another material, such as a plastics material, could be used.

The bullet trap 8, made of steel, has a conical aperture 17 made on itsrear surface which is designed to receive the bullet.

It is also provided with means of damping the impact of the bullet, hereconsisting of a collar 18.

The bullet trap 8 has a section of reduced diameter 19 on which a spacer20 is fitted, made for example of aluminium. One end of the spacer 20bears against the bullet trap and the other against the support 12 ofthe plug 13.

The bullet trap/spacer assembly is held in this position bearing on thesupport 12 by means of a nut 21 which is screwed into the cartridge tube1 and has an internal bore 22 which centers the bullet trap 8 relativeto the cartridge tube 1.

The spacer 20 maintains the bullet trap at a particular distance fromthe wall and therefore from the plug.

The distance between the bullet trap and the wall leaves an empty space42 between these components.

The distance between the bullet trap and the plug will be chosen suchthat the bullet trap 8 does not come into contact with the wall 15 asthe trap 8 deforms and also that there is an adequate volume of spacebetween the wall 15 and the bullet trap to accommodate the bulletfragments.

In practice, a distance of 5 to 10 mm can be adopted between the plugand the rear of the bullet trap.

The operation of the device is as follows:

When the grenade carrying the cartridge tube of the invention is fired,the bullet first passes through the thinned central portion 10 of thepartition wall 9, ignites the propellant composition in the cavity 11and then passes through the plug 13 and its support 12.

The wall 15 against which the plug bears holds the plug in positionrelative to the cartridge tube during its penetration by the bullet.

The bullet thus compresses the material of the plug, which material isretained axially by the wall.

As a result, the shearing of the plug is limited to the zone throughwhich the bullet passes. The closure of the plug is assisted and theplug can retain the fragments of the bullet.

Moreover, since the wall 15 is held at a distance from the bullet trap,the deformation of the trap during the impact of the bullet does notdamage the plug.

The bore 14 firmly holds the outer-surface of the plug which alsoassists in the closure of the plug.

In the embodiment described here, the plug has a rear part of diameterless than the bore 14. This difference in diameter allows the materialof the plug to expand radially during the impact of the bullet whichfacilitates the onset of penetration.

The rear part of the plug could be given a conical section. FIG. 2 showsa second embodiment of the cartridge tube according to the invention inwhich the wall 15 of the support 12 of the plug 13 has an opening 24having a diameter greater than that of the bullet.

The plug itself has no depression facing the wall 15. As the plug ispenetrated, the material of the plug will deform through the opening 24.The support 12 holds the plug 13 both axially and radially through itsbore 14 and its wall 15.

The bullet trap 8 has a cylindrical seat 23 which centers it relative tothe cartridge tube 1 and also forms an axial stop held against aninternal shoulder of the cartridge tube by the nut 21.

This stop ensures that the bullet trap is positioned at a distance fromthe wall.

FIG. 3 shows a different version of the support 13 of the plug, whichcan be used in either of the cartridge tubes described above.

The internal bore 14 in the support 12 has an annular rim 26 which isdesigned to keep the plug bearing on the wall 15 and which thus replacesthe elastic washer 16 described previously.

The plug 13 has a front chamfer 27 and the support 12 has a rear chamfer28. The plug 13 is press fitted into the support 12.

This fitting is facilitated by the presence of the chamfers 27 and 28and of the depression 25 which permits the elastic deformation of theplug.

In this way the plug is more rigidly gripped by the support and assemblyis also made easier.

In a different embodiment of the invention, the distance between thebullet trap and the plug will be given a particular value.

Thus, with reference to FIGS. 1 and 2, the length of the spacer 20 wouldbe chosen such that the distance D between the plug 13 and that part ofthe bullet trap on which the bullet impacts is greater than or equal tothe length of the bullet.

With the bullet traps shown in FIGS. 1 and 2, the bullet comes intocontact with the bullet trap at the conical opening 17 at about 2 mmfrom a rear surface 30 of the bullet trap.

Bullets of a given caliber may have different lengths according to theirballistic characteristics or their terminal effectiveness.

Thus, 5.56 mm caliber bullets available on the market have lengthssubstantially between 18 mm and 23 mm.

It is possible to choose a length D which is greater than the maximumpossible length of the bullet at the caliber considered, say 23 mm forthe 5.56.

It is also possible to choose a length D greater than the length of thebullet of the particular caliber which generates most fragments in theimpact on the bullet trap.

With these variants the bullet which generates most fragments hascompletely passed through the plug 13 when it comes into contact withthe bullet trap 8.

The plug will have closed again before this bullet impacts on the bullettrap, and therefore before the first fragments caused by this impact areprojected towards the rear of the cartridge tube. In this way theeffectiveness of the cartridge tube according to the invention isincreased.

It is possible, without departing from the framework of the invention,to combine one or other of the variants described for the means ofattaching the bullet trap with the different methods of making the plugsupport.

A propellant charge may or may not be placed inside the cavity 11.

The partition wall 9 may possibly be eliminated, whereupon the plugcarried by the support will then constitute a seal at the front 5 of thecartridge tube.

In this latter case, it is possible to glue the plug 13 on a wall 15obtained directly by machining the cartridge tube.

FIG. 4 describes a third embodiment of a cartridge tube according to theinvention. This particular method of construction allows the bulletfragments to be retained effectively while permitting the propellantgases generated by the munition to be used to ignite a rocket.

Igniting a rocket by utilizing gas is well known in the trade. ThusFrench patent 2567639 describes a grenade rocket mechanism whichutilizes the propellant gases. This mechanism includes an annular boltwhich retains a firing pin; the bolt is displaced by the pressure of thegases and releases the firing pin.

This mechanism does not form part of the present invention and willtherefore not be described in more detail.

The cartridge tube according to this third embodiment thereforecomprises a support 12 which is threaded on the cartridge tube 1. As inthe preceding variants, this support has a bore 14 which holds an outersurface of the plug 13. The plug is pressed by a cap 33 against abearing surface 31 attached to the support 12.

The bearing surface 31 is pierced by an opening 32 having a diametergreater than that of the bullet.

The cap 33 is threaded on the support 12. Thus, in this particularmethod of construction, the wall 15 is carried by the cap 33 whichcloses off the bore 14 and presses the plug 13 against the bearingsurface 31.

The cap 33 has a cylindrical extension 34 constituting a spacer againstwhich the bullet trap 8 bears. This spacer serves to maintain the bullettrap 8 at a distance from the wall 15 and thus establish an empty space42 between these items.

The bullet trap is maintained in this position bearing on the cap 33 bymeans of a nut 21 which is screwed into the cartridge tube 1 and has aninternal bore 22 which centers the bullet trap 8 relative to thecartridge tube 1.

As in the preceding methods of construction, the bullet trap 8 is madeof steel and has a conical opening 17 made in its rear surface and whichis designed to receive the bullet.

It is also fitted with means for damping the impact of the bullet, hereconsisting of a collar 18.

The distance between the bullet trap and the plug will be chosen suchthat the bullet trap 8 does not come into contact with the wall 15 asthe trap 8 deforms and also that there is a sufficient volume of spacebetween the wall 15 and the bullet trap to accommodate the bulletfragments.

A sealing ring 35 in plastics material is fitted both to the outercylindrical surface of the bullet trap 8 and to an external surface ofthe cylindrical extension 34 of the cap 33.

The support 12 also has at its rear end a chamber 36 which is designedto accommodate a charge of propellant powder if appropriate. Thischamber communicates with the rear part 2 of the cartridge tube throughan aperture 37.

The support 12 has four openings 38 distributed at regular angularintervals (see FIG. 5a), which are designed to allow some of thepropellant gases generated by the munition to pass towards the frontpart of the cartridge tube.

These gases will be able to act upon the mechanisms of the rocket (notshown) by passing through channels 39 (distributed at regular angularintervals) made in the nut 21.

A closure pad 40 is positioned on the rear surface of the support 12 toshut off the openings 38 and the opening 37 to prevent moisture frompenetrating into the cartridge tube during storage.

The plug 13 used in this particular method of construction incorporatesa depression 25 designed to be positioned facing the wall 15.

It also comprises four notches 41 made in its outer cylindrical surfaceand arranged at regular angular intervals (see FIG. 5b).

These notches allow the plug 18 to expand radially when it is penetratedby the bullet thus assisting perforation of the plug and its closureafter the bullet has passed, regardless the caliber of the bullet (5.56mm or 7.62 mm).

The operation of the device is similar to that previously described. Itwill be noted however that the openings 38 and channels 39 serve toignite the grenade rocket by means of the gases generated.

The ring 35 prevents the propellant gases from moving back towards theplug 13. Thus, the bullet fragments are retained by the plug and remaininside the empty space 42 bounded by the cylindrical extension 34 of thecap 33.

It is of course possible to combine the plug described in the frameworkof this particular method of construction, and which comprises notchesmade on its outer surface, with the variants of the cartridge tubesdescribed previously with reference to FIGS. 1 to 3.

We claim:
 1. A cartridge tube for a grenade fired from a rifle by a liveround, the tube comprising:a bullet trap for stopping a bullet; a plugmade of a deformable material for preventing fragments produced when thebullet impacts the bullet trap from escaping from the cartridge tube;and a support positioned between the plug and the bullet trap, saidsupport comprising a bore delimited by a wall such that said support hasa C-shaped cross-section, said bore retaining said plug, and said plugbearing against the wall, the wall being disposed between said bore andsaid bullet trap and attached to the cartridge tube and substantiallyperpendicular to a center line of the tube, the wall being positioned ata distance from the bullet trap along the center-line of the cartridgetube to create a space between the wall and the bullet trap.
 2. Thecartridge tube according to claim 1 wherein the plug has a depressionfacing the wall.
 3. The cartridge tube according to claim 1, wherein theplug has a plurality of notches arranged at uniform intervals on anouter surface of the plug.
 4. The cartridge tube according to claim 1,wherein the wall has a substantially central opening therethrough havinga diameter greater than a diameter of the bullet.
 5. The cartridge tubeaccording to claim 1, wherein the plug has a rear portion with adiameter less than a diameter of the bore in the support.
 6. Thecartridge tube according to claim 1, wherein the support rests against aspacer disposed between said support and said bullet trap said wallresting against said spacer.
 7. The cartridge tube according to claim 6,wherein the bore of the support has an annular rim to hold the plug inan axial direction.
 8. The cartridge tube according to claim 1, whereina distance between the deformable plug and a part of the bullet trapwhich the bullet first contacts is greater than the total length of thebullet.
 9. A cartridge tube for a grenade fired from a rifle by a liveround, the tube comprising:a bullet trap for stopping a bullet; a plugmade of a deformable material for preventing fragments produced when thebullet impacts the bullet trap from escaping from the cartridge tube; awall positioned between the plug and the bullet trap, said plug bearingagainst the wall, the wall being attached to the cartridge tube andsubstantially perpendicular to a center line of the tube, the wall beingpositioned at a distance from the bullet trap along the center line ofthe cartridge tube to create a space between the wall and the bullettrap; and a support, wherein the wall is attached to said support andsaid support is attached to the cartridge tube, said support comprisinga bore that holds an outer surface of the plug, wherein the support hasa bearing surface on which the plug bears, said wall being attached to acap that closes off the bore and presses the plug against the bearingsurface, and wherein the support has a plurality of openings allowing aportion of propellant gasses generated by a munition to pass to ignite arocket, said support further comprising a sealing ring fitted on anouter surface of the bullet trap and on a cylindrical extension of thecap.
 10. The cartridge tube according to claim 9, wherein thecylindrical extension of the cap comprises a spacer that bears againstthe bullet trap and holds said trap at a distance from the wall.